Controlling Transformation of Sorbitol into 1-Hexanol over Ru-MoOx/Mo2C Catalyst via Aqueous-Phase Hydrodeoxygenation

Higher alcohols are important monohydric alcohols category of synthetic chemicals and fuels. Currently, research efforts in this catalytic synthesis have been devoted to providing desirable selectivity to specific higher alcohols. In this work, for the first time, the aqueous-phase hydrodeoxygenation of sorbitol derived from biomass was proposed to efficiently synthesize renewable 1-hexanol over a multifunctional Ru-MoOx/Mo2C catalyst in a continuous-flow tubular reactor. Compared with molybdenum nitride, phosphide, sulfide, and oxide catalysts, molybdenum carbide displayed promising catalytic performance in the selective transformation of sorbitol into 1-hexanol, representing the feasibility of selectively controlling the C-O bond cleavage and preserving the original carbon chain. Studies in catalyst characterization revealed that the synergism of Ru and Mo2C was the key to manipulate the main product selectivity between 1-hexanol and 1-hexane, while the 1-hexanol selectivity was concurrently promoted by the presence of MoOx. The highest yield (28.7%) of 1-hexanol was achieved at 523 K under 6.0 MPa of hydrogen pressure. The present catalyst system was equally applicable to the selective hydrogenolysis of other sugar polyols such as xylitol, erythritol, glycerin, and ethylene glycol into the corresponding 1-pentanol, 1-butanol, 1-propanol, and ethanol. Thus, this catalytic strategy creates new opportunities for producing high value-added higher alcohols from sugar polyols over molybdenum carbide materials.